What do you mean by "weird"? There are several different approaches, although with limited crossover possibilities:
1945+ Continuation war (all the paper panzers, jets, walkers/mechs, hi tech weaponry etc)
Cthulhu, Zombies, Ark of the Covenant, magic and super science.
Traditional Golden Age comics and Superheroes.
In 6mm the first is far and away the simplest to do as most kit can be sourced from WW2 and Cold War microtank ranges and Battletech or original release GW epic pieces.
The second would use the same WW2 microarmour kit with suitable monsters from Fantasy ranges, boardgame pieces etc (loads of options up to 15mm scale figures would be OK)
The last one probably the most difficult as 6mm is not really suited to individual models so identifying characters would be hard.